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278 lines
6.5 KiB
PHP
278 lines
6.5 KiB
PHP
<?php
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/** @file spldoublylinkedlist.inc
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* @ingroup SPL
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* @brief class SplDoublyLinkedList
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* @author Etienne Kneuss
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* @date 2008 - 2009
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*
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* SPL - Standard PHP Library
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*/
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/** @ingroup SPL
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* @brief Doubly Linked List
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* @since PHP 5.3
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*
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* The SplDoublyLinkedList class provides the main functionalities of a
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* doubly linked list (DLL).
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* @note The following userland implementation of Iterator is a bit different
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* from the internal one. Internally, iterators generated by nested
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* foreachs are independent, while they share the same traverse pointer
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* in userland.
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*/
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class SplDoublyLinkedList implements Iterator, ArrayAccess, Countable
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{
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protected $_llist = array();
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protected $_it_mode = 0;
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protected $_it_pos = 0;
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/** Iterator mode
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* @see setIteratorMode
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*/
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const IT_MODE_LIFO = 0x00000002;
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/** Iterator mode
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* @see setIteratorMode
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*/
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const IT_MODE_FIFO = 0x00000000;
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/** Iterator mode
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* @see setIteratorMode
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*/
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const IT_MODE_KEEP = 0x00000000;
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/** Iterator mode
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* @see setIteratorMode
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*/
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const IT_MODE_DELETE = 0x00000001;
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/** @return the element popped from the end of the DLL.
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* @throw RuntimeException If the datastructure is empty.
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*/
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public function pop()
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{
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if (count($this->_llist) == 0) {
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throw new RuntimeException("Can't pop from an empty datastructure");
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}
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return array_pop($this->_llist);
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}
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/** @return the element shifted from the beginning of the DLL.
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* @throw RuntimeException If the datastructure is empty.
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*/
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public function shift()
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{
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if (count($this->_llist) == 0) {
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throw new RuntimeException("Can't shift from an empty datastructure");
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}
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return array_shift($this->_llist);
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}
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/** Pushes an element to the end of the DLL.
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* @param $data variable to add to the DLL.
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*/
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public function push($data)
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{
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array_push($this->_llist, $data);
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return true;
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}
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/** Adds an element to the beginning of the DLL.
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* @param $data variable to add to the DLL.
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*/
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public function unshift($data)
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{
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array_unshift($this->_llist, $data);
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return true;
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}
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/** @return the element at the beginning of the DLL.
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*/
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public function top()
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{
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return end($this->_llist);
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}
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/** @return the element at the end of the DLL.
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*/
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public function bottom()
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{
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return reset($this->_llist);
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}
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/** @return number elements in the DLL.
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*/
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public function count()
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{
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return count($this->_llist);
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}
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/** @return whether the DLL is empty.
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*/
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public function isEmpty()
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{
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return ($this->count() == 0);
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}
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/** Changes the iteration mode. There are two orthogonal sets of modes that
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* can be set:
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* - The direction of the iteration (either one or the other)
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* - SplDoublyLnkedList::IT_MODE_LIFO (Stack style)
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* - SplDoublyLnkedList::IT_MODE_FIFO (Queue style)
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*
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* - The behavior of the iterator (either one or the other)
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* - SplDoublyLnkedList::IT_MODE_DELETE (Elements are deleted by the iterator)
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* - SplDoublyLnkedList::IT_MODE_KEEP (Elements are traversed by the iterator)
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*
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* The default mode is 0 : SplDoublyLnkedList::IT_MODE_FIFO | SplDoublyLnkedList::IT_MODE_KEEP
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*
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* @param $mode new mode of iteration
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*/
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public function setIteratorMode($mode)
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{
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$this->_it_mode = $mode;
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}
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/** @return the current iteration mode
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* @see setIteratorMode
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*/
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public function getIteratorMode()
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{
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return $this->_it_mode;
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}
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/** Rewind to top iterator as set in constructor
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*/
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public function rewind()
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{
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if ($this->_it_mode & self::IT_MODE_LIFO) {
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$this->_it_pos = count($this->_llist)-1;
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} else {
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$this->_it_pos = 0;
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}
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}
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/** @return whether iterator is valid
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*/
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public function valid()
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{
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return array_key_exists($this->_it_pos, $this->_llist);
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}
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/** @return current key
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*/
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public function key()
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{
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return $this->_it_pos;
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}
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/** @return current object
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*/
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public function current()
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{
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return $this->_llist[$this->_it_pos];
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}
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/** Forward to next element
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*/
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public function next()
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{
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if ($this->_it_mode & self::IT_MODE_LIFO) {
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if ($this->_it_mode & self::IT_MODE_DELETE) {
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$this->pop();
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}
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$this->_it_pos--;
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} else {
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if ($this->_it_mode & self::IT_MODE_DELETE) {
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$this->shift();
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} else {
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$this->_it_pos++;
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}
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}
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}
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/** @return whether a certain offset exists in the DLL
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*
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* @param $offset The offset
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* @throw OutOfRangeException If the offset is either invalid or out of
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* range.
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*/
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public function offsetExists($offset)
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{
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if (!is_numeric($offset)) {
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throw new OutOfRangeException("Offset invalid or out of range");
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} else {
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return array_key_exists($offset, $this->_llist);
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}
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}
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/** @return the data at a certain offset in the DLL
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*
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* @param $offset The offset
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* @throw OutOfRangeException If the offset is either invalid or out of
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* range.
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*/
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public function offsetGet($offset)
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{
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if ($this->_it_mode & self::IT_MODE_LIFO) {
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$realOffset = count($this->_llist)-$offset;
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} else {
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$realOffset = $offset;
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}
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if (!is_numeric($offset) || !array_key_exists($realOffset, $this->_llist)) {
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throw new OutOfRangeException("Offset invalid or out of range");
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} else {
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return $this->_llist[$realOffset];
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}
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}
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/** Defines the data at a certain offset in the DLL
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*
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* @param $offset The offset
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* @param $value New value
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* @throw OutOfRangeException If the offset is either invalid or out of
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* range.
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*/
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public function offsetSet($offset, $value)
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{
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if ($offset === null) {
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return $this->push($value);
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}
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if ($this->_it_mode & self::IT_MODE_LIFO) {
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$realOffset = count($this->_llist)-$offset;
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} else {
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$realOffset = $offset;
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}
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if (!is_numeric($offset) || !array_key_exists($realOffset, $this->_llist)) {
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throw new OutOfRangeException("Offset invalid or out of range");
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} else {
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$this->_llist[$realOffset] = $value;
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}
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}
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/** Unsets the element at a certain offset in the DLL
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*
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* @param $offset The offset
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* @throw OutOfRangeException If the offset is either invalid or out of
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* range.
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*/
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public function offsetUnset($offset)
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{
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if ($this->_it_mode & self::IT_MODE_LIFO) {
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$realOffset = count($this->_llist)-$offset;
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} else {
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$realOffset = $offset;
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}
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if (!is_numeric($offset) || !array_key_exists($realOffset, $this->_llist)) {
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throw new OutOfRangeException("Offset invalid or out of range");
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} else {
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array_splice($this->_llist, $realOffset, 1);
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}
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}
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}
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?>
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